1. Field of the Invention
The present invention relates to a container which stores liquids such as highly purified chemicals for semiconductors and ordinary chemical agents, and a plug for such a container.
2. Description of the Related Art
Generally, a semiconductor high pure chemical and an ordinary chemical agent are stored in containers which are resistable to such agents.
Formally, as shown in FIG. 16, two openings 1a are formed in this container 1, plugs 2 each of which has a plug section (not shown in the drawing) are positioned in these openings 1a. These plugs 2 function as lids which close the openings 1a, one is a plug 2a for connection to the liquid path, and the other one is a plug 2b for connection to the gas path, and a pipe 3 which extends to the vicinity of the bottom of the container 1 is connected to the liquid path plug 2a for connection to the liquid path.
Also, a cap is put on the plug sections of each plug 2 positioned in the openings la in this type of container 1, the through hole which is formed in the plug section is closed by this cap, and the liquid in this container is carried or stored in this state.
Consequently, when taking out the liquids stored in this container 1, firstly, after the caps which had been put on the plug sections of the plugs 2 which were positioned in the openings 1a are removed, sockets 5 connected with hoses 4 are connected to the plug sections of these plugs 2, and the liquid inside the container 1 is drawn out into the hose 4 by way of the pipe by a pump P.
Additionally, at this time, inert gas is fed into the container 1 from the hose 4 which is connected to the plug section of the plug 2b on the other side in such a way that the pressure inside of the container 1 is not negative. Also, it can be determined by the flow of gas on the gas drawing-side whether all the liquid inside the container 1 was fed out and whether the container 1 has become empty. Consequently, when a gas flow is detected, it is determined that the inside of the container 1 is empty, and this empty container 1 can be replaced by a new container 1 in which liquid is stored.
There are the cases in which the liquid inside the container 1 vaporizes as time goes by, so there is concern that the internal pressure increases during use. This occurs particularly when the liquid inside the container 1 is volatile.
Therefore, if the cap of the plug section of plug 2a for connection with the liquid path is detached when the internal pressure is high in this way, there is concern that the liquid will leak travel along the way of the pipe 3 and leak from the through hole of the plug section because of the internal pressure of the container 1.
For this reason, a sign is placed on the plug 2a on which the pipe 3 is provided indicating that the plug 2a is to be used for connection with the liquid path, and a sign is placed on the other plug 2b on which pipe 3 is not provided, indicating that the plug 2b is to be used for connection with the gas path. An operator detaches the cap put on the plug section of plug 2a for connection with liquid path, after identifying the signs on these plugs 2a and 2b and taking out the cap which was put on the plug section of plug 2a for connection with the gas path from the plug in order to lower the internal pressure of the container 1.
However, with the above container 1, the removal of the caps in turn has to be performed only according to the signs on the plugs 2a and 2b; therefore an improvement in safety is desired.
The present invention was made in light of the above situation, and an object of the present invention is to a provide a container and plugs for the container with greater safety such that liquid does not leak due to the internal pressure during use.